1. Technical Field
The present invention generally relates to a cable television (CATV) interdiction system and, more particularly, to a CATV interdiction system including an improved method and apparatus for diagnosing various types of problems in a remote interdiction unit.
2. Description of the Prior Art
The cable television industry has recently resorted to new technologies and has taken a second look at technologies developed in the early stages of development of cable television including negative and positive trap technology and interdiction systems to remove equipment off the subscriber's premises. A CATV interdiction system manufactured by Scientific-Atlanta, Inc., and described by U.S. Pat. No. 4,912,760, evidences one product manufacturer's response to such concerns. Precipitating the removal of equipment from the subscribers' premises has been the provision of television channel conversion equipment within the new television receivers sold today and the predominace of so-called cable ready receivers. In other words, the converter portions of converter/decoders are in many instances no longer required. Also, removal of equipment from the subscribers' premises accomplished a removal of equipment from the hands of pirates. The interdiction system described by U.S. Pat. No. 4,912,760 promotes the removal of all CATV equipment from a CATV service subscriber's premise except for equipment for certain special service applications such as pay per view services.
Most embodiments promoted by manufacturers of interdiction systems consist of a pole-mounted or side of building mounted enclosures located outside the subscriber's premises designed to serve four or more subscribers. This enclosure contains at least one microprocessor controlled oscillator and switch control electronics to secure several several television channels. Control is accomplished by injecting an interfering or jamming signal into unauthorized channels from this enclosure.
In the Scientific-Atlanta system to improve efficiency and to save costs, each of a plurality of oscillators may be used to jam several premium television channels in a continuous band of frequencies selected from the broadband 50-550 megahertz (MHz) or other spectrum. This technique not only reduces the amount of hardware required, but also maximizes the system flexibility. The oscillator output jamming signal frequency is periodically moved from channel to channel. Consequently, the oscillator is frequency agile and hops from jamming one premium channel frequency to the next.
Cost reduction is achieved in the systems discussed above, i.e. trap and interdiction systems, by providing shared housings outside the subscriber's premises for each of a plurality of subscriber units, for example, four such units and common circuitry associated with the several subscriber units. Common control circuitry is shown in FIG. 2 of U.S. Pat. No. 4,912,760. These housings are mounted out-of-doors on poles or in pedestals for serving especially suburban subscribers. Further details of such housing apparatus is also provided by U.S. Pat. No. 4,963,966. Also, indoor housings are known from so-called multiple dwelling unit systems where a cable television system supplies service to apartment building or condominium complexes. In more suburban and rural environs, a single port (subscriber) unit may be provided which may, for example, be mounted to the side of an exterior of a subscriber's home.
Because of the nature of the interdiction units, various problems might occur in their operation--one or more components within the unit might fail, the connection with the headend might fail, power might be removed from the unit for one of several reasons, or persons may tamper with the unit. In the past, when such problems occurred, the subscriber's television service would be completely cut off or would be degraded or modified to a certain extent. For example, if the cover of the interdiction unit was opened by someone other than authorized personnel, circuitry within the unit would completely diable the unit, and service would be completely cut off to the subscriber(s). If the communication link or a component within the unit failed, subscriber television service would either be completely cut off or some other adverse effect on the television signal would likely occur.
Previously, when problems occurred in the operation of a subscriber's cable television service, the subscriber had to report the problem to the cable television operator, and a technician had to be dispatched to the subscriber's interdiction unit to determine the cause of the problem. Typically, the technician had no way of knowing the cause of the problem before physically examining the interdiction unit. The personnel at the headend usually had no way of determining the nature of the problem based upon the information provided by the subscriber. Therefore, the cable operator had no way of determining whether the problem could simply be fixed without sending a technician to the site, and the technician had no way of determining what types of tools might be necessary to fix the problem with the interdiction unit. As a result, the technician may need to make several trips to the sit of the interdiction unit in order to determine the problem and to obtain the proper tools to correct the problem, or the technician had to attempt to carry every conceivable tool which might be necessary to fix the problem with the interdiction unit.